/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.authenticator;

import java.io.IOException;
import java.io.InputStream;
import java.security.Principal;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Locale;

import javax.servlet.RequestDispatcher;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.Globals;
import org.apache.catalina.Realm;
import org.apache.catalina.Session;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.deploy.LoginConfig;
import org.apache.coyote.ActionCode;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.CharChunk;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.http.MimeHeaders;

/**
 * An <b>Authenticator</b> and <b>Valve</b> implementation of FORM BASED
 * Authentication, as described in the Servlet API Specification, Version 2.2.
 * 
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 * @version $Id: FormAuthenticator.java 1066314 2011-02-02 03:03:08Z kkolinko $
 */

public class FormAuthenticator extends AuthenticatorBase {

	private static Log log = LogFactory.getLog(FormAuthenticator.class);

	// ----------------------------------------------------- Instance Variables

	/**
	 * Descriptive information about this implementation.
	 */
	protected static final String info = "org.apache.catalina.authenticator.FormAuthenticator/1.0";

	/**
	 * Character encoding to use to read the username and password parameters
	 * from the request. If not set, the encoding of the request body will be
	 * used.
	 */
	protected String characterEncoding = null;

	// ------------------------------------------------------------- Properties

	/**
	 * Return descriptive information about this Valve implementation.
	 */
	public String getInfo() {

		return (info);

	}

	/**
	 * Return the character encoding to use to read the username and password.
	 */
	public String getCharacterEncoding() {
		return characterEncoding;
	}

	/**
	 * Set the character encoding to be used to read the username and password.
	 */
	public void setCharacterEncoding(String encoding) {
		characterEncoding = encoding;
	}

	// --------------------------------------------------------- Public Methods

	/**
	 * Authenticate the user making this request, based on the specified login
	 * configuration. Return <code>true</code> if any specified constraint has
	 * been satisfied, or <code>false</code> if we have created a response
	 * challenge already.
	 * 
	 * @param request
	 *            Request we are processing
	 * @param response
	 *            Response we are creating
	 * @param config
	 *            Login configuration describing how authentication should be
	 *            performed
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public boolean authenticate(Request request, Response response,
			LoginConfig config) throws IOException {

		// References to objects we will need later
		Session session = null;

		// Have we already authenticated someone?
		Principal principal = request.getUserPrincipal();
		String ssoId = (String) request.getNote(Constants.REQ_SSOID_NOTE);
		if (principal != null) {
			if (log.isDebugEnabled())
				log
						.debug("Already authenticated '" + principal.getName()
								+ "'");
			// Associate the session with any existing SSO session
			if (ssoId != null)
				associate(ssoId, request.getSessionInternal(true));
			return (true);
		}

		// Is there an SSO session against which we can try to reauthenticate?
		if (ssoId != null) {
			if (log.isDebugEnabled())
				log.debug("SSO Id " + ssoId + " set; attempting "
						+ "reauthentication");
			// Try to reauthenticate using data cached by SSO. If this fails,
			// either the original SSO logon was of DIGEST or SSL (which
			// we can't reauthenticate ourselves because there is no
			// cached username and password), or the realm denied
			// the user's reauthentication for some reason.
			// In either case we have to prompt the user for a logon */
			if (reauthenticateFromSSO(ssoId, request))
				return true;
		}

		// Have we authenticated this user before but have caching disabled?
		if (!cache) {
			session = request.getSessionInternal(true);
			if (log.isDebugEnabled())
				log.debug("Checking for reauthenticate in session " + session);
			String username = (String) session
					.getNote(Constants.SESS_USERNAME_NOTE);
			String password = (String) session
					.getNote(Constants.SESS_PASSWORD_NOTE);
			if ((username != null) && (password != null)) {
				if (log.isDebugEnabled())
					log.debug("Reauthenticating username '" + username + "'");
				principal = context.getRealm().authenticate(username, password);
				if (principal != null) {
					session.setNote(Constants.FORM_PRINCIPAL_NOTE, principal);
					if (!matchRequest(request)) {
						register(request, response, principal,
								Constants.FORM_METHOD, username, password);
						return (true);
					}
				}
				if (log.isDebugEnabled())
					log.debug("Reauthentication failed, proceed normally");
			}
		}

		// Is this the re-submit of the original request URI after successful
		// authentication? If so, forward the *original* request instead.
		if (matchRequest(request)) {
			session = request.getSessionInternal(true);
			if (log.isDebugEnabled())
				log.debug("Restore request from session '"
						+ session.getIdInternal() + "'");
			principal = (Principal) session
					.getNote(Constants.FORM_PRINCIPAL_NOTE);
			register(request, response, principal, Constants.FORM_METHOD,
					(String) session.getNote(Constants.SESS_USERNAME_NOTE),
					(String) session.getNote(Constants.SESS_PASSWORD_NOTE));
			// If we're caching principals we no longer need the username
			// and password in the session, so remove them
			if (cache) {
				session.removeNote(Constants.SESS_USERNAME_NOTE);
				session.removeNote(Constants.SESS_PASSWORD_NOTE);
			}
			if (restoreRequest(request, session)) {
				if (log.isDebugEnabled())
					log.debug("Proceed to restored request");
				return (true);
			} else {
				if (log.isDebugEnabled())
					log.debug("Restore of original request failed");
				response.sendError(HttpServletResponse.SC_BAD_REQUEST);
				return (false);
			}
		}

		// Acquire references to objects we will need to evaluate
		MessageBytes uriMB = MessageBytes.newInstance();
		CharChunk uriCC = uriMB.getCharChunk();
		uriCC.setLimit(-1);
		String contextPath = request.getContextPath();
		String requestURI = request.getDecodedRequestURI();
		response.setContext(request.getContext());

		// Is this the action request from the login page?
		boolean loginAction = requestURI.startsWith(contextPath)
				&& requestURI.endsWith(Constants.FORM_ACTION);

		// No -- Save this request and redirect to the form login page
		if (!loginAction) {
			session = request.getSessionInternal(true);
			if (log.isDebugEnabled())
				log.debug("Save request in session '" + session.getIdInternal()
						+ "'");
			try {
				saveRequest(request, session);
			} catch (IOException ioe) {
				log.debug("Request body too big to save during authentication");
				response.sendError(HttpServletResponse.SC_FORBIDDEN, sm
						.getString("authenticator.requestBodyTooBig"));
				return (false);
			}
			forwardToLoginPage(request, response, config);
			return (false);
		}

		// Yes -- Acknowledge the request, validate the specified credentials
		// and redirect to the error page if they are not correct
		response.sendAcknowledgement();
		Realm realm = context.getRealm();
		if (characterEncoding != null) {
			request.setCharacterEncoding(characterEncoding);
		}
		String username = request.getParameter(Constants.FORM_USERNAME);
		String password = request.getParameter(Constants.FORM_PASSWORD);
		if (log.isDebugEnabled())
			log.debug("Authenticating username '" + username + "'");
		principal = realm.authenticate(username, password);
		if (principal == null) {
			forwardToErrorPage(request, response, config);
			return (false);
		}

		if (log.isDebugEnabled())
			log.debug("Authentication of '" + username + "' was successful");

		if (session == null)
			session = request.getSessionInternal(false);
		if (session == null) {
			if (containerLog.isDebugEnabled())
				containerLog
						.debug("User took so long to log on the session expired");
			response.sendError(HttpServletResponse.SC_REQUEST_TIMEOUT, sm
					.getString("authenticator.sessionExpired"));
			return (false);
		}

		// Save the authenticated Principal in our session
		session.setNote(Constants.FORM_PRINCIPAL_NOTE, principal);

		// Save the username and password as well
		session.setNote(Constants.SESS_USERNAME_NOTE, username);
		session.setNote(Constants.SESS_PASSWORD_NOTE, password);

		// Redirect the user to the original request URI (which will cause
		// the original request to be restored)
		requestURI = savedRequestURL(session);
		if (log.isDebugEnabled())
			log.debug("Redirecting to original '" + requestURI + "'");
		if (requestURI == null)
			response.sendError(HttpServletResponse.SC_BAD_REQUEST, sm
					.getString("authenticator.formlogin"));
		else
			response.sendRedirect(response.encodeRedirectURL(requestURI));
		return (false);

	}

	// ------------------------------------------------------ Protected Methods

	/**
	 * Called to forward to the login page
	 * 
	 * @param request
	 *            Request we are processing
	 * @param response
	 *            Response we are creating
	 * @param config
	 *            Login configuration describing how authentication should be
	 *            performed
	 * @throws IOException
	 *             If the forward to the login page fails and the call to
	 *             {@link HttpServletResponse#sendError(int, String) throws an
	 *             {@link IOException}
	 */
	protected void forwardToLoginPage(Request request, Response response,
			LoginConfig config) throws IOException {
		RequestDispatcher disp = context.getServletContext()
				.getRequestDispatcher(config.getLoginPage());
		try {
			disp.forward(request.getRequest(), response.getResponse());
			response.finishResponse();
		} catch (Throwable t) {
			String msg = sm.getString("formAuthenticator.forwardLoginFail");
			log.warn(msg, t);
			request.setAttribute(Globals.EXCEPTION_ATTR, t);
			response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
					msg);
		}
	}

	/**
	 * Called to forward to the error page
	 * 
	 * @param request
	 *            Request we are processing
	 * @param response
	 *            Response we are creating
	 * @param config
	 *            Login configuration describing how authentication should be
	 *            performed
	 * @throws IOException
	 *             If the forward to the error page fails and the call to
	 *             {@link HttpServletResponse#sendError(int, String) throws an
	 *             {@link IOException}
	 */
	protected void forwardToErrorPage(Request request, Response response,
			LoginConfig config) throws IOException {
		RequestDispatcher disp = context.getServletContext()
				.getRequestDispatcher(config.getErrorPage());
		try {
			disp.forward(request.getRequest(), response.getResponse());
		} catch (Throwable t) {
			String msg = sm.getString("formAuthenticator.forwardErrorFail");
			log.warn(msg, t);
			request.setAttribute(Globals.EXCEPTION_ATTR, t);
			response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
					msg);
		}
	}

	/**
	 * Does this request match the saved one (so that it must be the redirect we
	 * signalled after successful authentication?
	 * 
	 * @param request
	 *            The request to be verified
	 */
	protected boolean matchRequest(Request request) {

		// Has a session been created?
		Session session = request.getSessionInternal(false);
		if (session == null)
			return (false);

		// Is there a saved request?
		SavedRequest sreq = (SavedRequest) session
				.getNote(Constants.FORM_REQUEST_NOTE);
		if (sreq == null)
			return (false);

		// Is there a saved principal?
		if (session.getNote(Constants.FORM_PRINCIPAL_NOTE) == null)
			return (false);

		// Does the request URI match?
		String requestURI = request.getRequestURI();
		if (requestURI == null)
			return (false);
		return (requestURI.equals(sreq.getRequestURI()));

	}

	/**
	 * Restore the original request from information stored in our session. If
	 * the original request is no longer present (because the session timed
	 * out), return <code>false</code>; otherwise, return <code>true</code>.
	 * 
	 * @param request
	 *            The request to be restored
	 * @param session
	 *            The session containing the saved information
	 */
	protected boolean restoreRequest(Request request, Session session)
			throws IOException {

		// Retrieve and remove the SavedRequest object from our session
		SavedRequest saved = (SavedRequest) session
				.getNote(Constants.FORM_REQUEST_NOTE);
		session.removeNote(Constants.FORM_REQUEST_NOTE);
		session.removeNote(Constants.FORM_PRINCIPAL_NOTE);
		if (saved == null)
			return (false);

		// Modify our current request to reflect the original one
		request.clearCookies();
		Iterator cookies = saved.getCookies();
		while (cookies.hasNext()) {
			request.addCookie((Cookie) cookies.next());
		}

		MimeHeaders rmh = request.getCoyoteRequest().getMimeHeaders();
		rmh.recycle();
		boolean cachable = "GET".equalsIgnoreCase(saved.getMethod())
				|| "HEAD".equalsIgnoreCase(saved.getMethod());
		Iterator names = saved.getHeaderNames();
		while (names.hasNext()) {
			String name = (String) names.next();
			// The browser isn't expecting this conditional response now.
			// Assuming that it can quietly recover from an unexpected 412.
			// BZ 43687
			if (!("If-Modified-Since".equalsIgnoreCase(name) || (cachable && "If-None-Match"
					.equalsIgnoreCase(name)))) {
				Iterator values = saved.getHeaderValues(name);
				while (values.hasNext()) {
					rmh.addValue(name).setString((String) values.next());
				}
			}
		}

		request.clearLocales();
		Iterator locales = saved.getLocales();
		while (locales.hasNext()) {
			request.addLocale((Locale) locales.next());
		}

		request.getCoyoteRequest().getParameters().recycle();
		request.getCoyoteRequest().getParameters().setQueryStringEncoding(
				request.getConnector().getURIEncoding());

		if ("POST".equalsIgnoreCase(saved.getMethod())) {
			ByteChunk body = saved.getBody();

			if (body != null) {
				request.getCoyoteRequest().action(
						ActionCode.ACTION_REQ_SET_BODY_REPLAY, body);

				// Set content type
				MessageBytes contentType = MessageBytes.newInstance();

				// If no content type specified, use default for POST
				String savedContentType = saved.getContentType();
				if (savedContentType == null) {
					savedContentType = "application/x-www-form-urlencoded";
				}

				contentType.setString(savedContentType);
				request.getCoyoteRequest().setContentType(contentType);
			}
		}
		request.getCoyoteRequest().method().setString(saved.getMethod());

		request.getCoyoteRequest().queryString().setString(
				saved.getQueryString());

		request.getCoyoteRequest().requestURI()
				.setString(saved.getRequestURI());
		return (true);

	}

	/**
	 * Save the original request information into our session.
	 * 
	 * @param request
	 *            The request to be saved
	 * @param session
	 *            The session to contain the saved information
	 * @throws IOException
	 */
	protected void saveRequest(Request request, Session session)
			throws IOException {

		// Create and populate a SavedRequest object for this request
		SavedRequest saved = new SavedRequest();
		Cookie cookies[] = request.getCookies();
		if (cookies != null) {
			for (int i = 0; i < cookies.length; i++)
				saved.addCookie(cookies[i]);
		}
		Enumeration names = request.getHeaderNames();
		while (names.hasMoreElements()) {
			String name = (String) names.nextElement();
			Enumeration values = request.getHeaders(name);
			while (values.hasMoreElements()) {
				String value = (String) values.nextElement();
				saved.addHeader(name, value);
			}
		}
		Enumeration locales = request.getLocales();
		while (locales.hasMoreElements()) {
			Locale locale = (Locale) locales.nextElement();
			saved.addLocale(locale);
		}

		if ("POST".equalsIgnoreCase(request.getMethod())) {
			// May need to acknowledge a 100-continue expectation
			request.getResponse().sendAcknowledgement();

			ByteChunk body = new ByteChunk();
			body.setLimit(request.getConnector().getMaxSavePostSize());

			byte[] buffer = new byte[4096];
			int bytesRead;
			InputStream is = request.getInputStream();

			while ((bytesRead = is.read(buffer)) >= 0) {
				body.append(buffer, 0, bytesRead);
			}
			saved.setContentType(request.getContentType());
			saved.setBody(body);
		}

		saved.setMethod(request.getMethod());
		saved.setQueryString(request.getQueryString());
		saved.setRequestURI(request.getRequestURI());

		// Stash the SavedRequest in our session for later use
		session.setNote(Constants.FORM_REQUEST_NOTE, saved);

	}

	/**
	 * Return the request URI (with the corresponding query string, if any) from
	 * the saved request so that we can redirect to it.
	 * 
	 * @param session
	 *            Our current session
	 */
	protected String savedRequestURL(Session session) {

		SavedRequest saved = (SavedRequest) session
				.getNote(Constants.FORM_REQUEST_NOTE);
		if (saved == null)
			return (null);
		StringBuffer sb = new StringBuffer(saved.getRequestURI());
		if (saved.getQueryString() != null) {
			sb.append('?');
			sb.append(saved.getQueryString());
		}
		return (sb.toString());

	}

}
